// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

/*
 * This file may have been modified by Bytedance Ltd. and/or its affiliates (“ Bytedance's Modifications”).
 * All Bytedance's Modifications are Copyright (2023) Bytedance Ltd. and/or its affiliates.
 */

#pragma once

#include <vector>

#include <stdint.h>
#include <Common/Slice.h>

namespace DB::IndexFile
{
struct Options;

class BlockBuilder
{
public:
    explicit BlockBuilder(const Options * options);

    // Reset the contents as if the BlockBuilder was just constructed.
    void Reset();

    // REQUIRES: Finish() has not been called since the last call to Reset().
    // REQUIRES: key is larger than any previously added key
    void Add(const Slice & key, const Slice & value);

    // Finish building the block and return a slice that refers to the
    // block contents.  The returned slice will remain valid for the
    // lifetime of this builder or until Reset() is called.
    Slice Finish();

    // Returns an estimate of the current (uncompressed) size of the block
    // we are building.
    size_t CurrentSizeEstimate() const;

    // Return true iff no entries have been added since the last Reset()
    bool empty() const { return buffer_.empty(); }

private:
    const Options * options_;
    std::string buffer_; // Destination buffer
    std::vector<uint32_t> restarts_; // Restart points
    int counter_; // Number of entries emitted since restart
    bool finished_; // Has Finish() been called?
    std::string last_key_;

    // No copying allowed
    BlockBuilder(const BlockBuilder &);
    void operator=(const BlockBuilder &);
};

}
